On the other hand, here are some organic ways that I've found useful for strengthening my level of concentration, independent of my programmming focus:

- working out regularly, especially running long distance

- playing games competitively (eg: chess, bridge, go)

- training your mind/memory or practicing mental arithmetic

- eat blueberries daily (random tip from Nelson Dellis, the current US Memory Champ: http://climbformemory.com/2011/01/05/blueberries-rock-my-bra...)